Field of the Invention
The invention relates generally to a shutter mechanism for a photographic camera, and in particular to novel bounce control means for preventing a shutter blade at the end of its closing movement from bouncing off a fixed stop and thereby possibly uncovering the lens opening to cause an undesired second exposure.
Description of the Prior Art
A shutter mechanism may be defined conventionally as a mechanical system for controling the time during which light is allowed to reach film in a camera. The shutter mechanism consists of some means, e.g. one or more opaque blades, for normally covering a lens opening to prevent light from reaching the film, uncovering the lens opening for a pre-set time to expose the film, and recovering the lens opening to terminate the exposure.
A typical shutter mechanism commonly used in lower price cameras, and generally referred to as an "impact" or "inertial" shutter, is illustrated in FIG. 1 of the accompanying drawings. As shown, a single shutter blade 1 is mounted for pivotal opening movement and pivotal closing movement in opposite counterclockwise and clockwise directions about a fixed pivot 3 to uncover and recover a lens opening 5. A return spring 7 biases the shutter blade 1 in the direction of closing movement, and usually serves to hold the blade in a closed position against a fixed stop 9 during non-exposure periods. The fixed stop 9 is positioned in the return path of the shutter blade 1 to end closing movement of the blade.
Upon manual actuation of a shutter release in the camera, a high speed impact member or striker 11 is released to strike the shutter blade 1 in its closed position. This actuates the shutter blade 1 to swing counterclockwise in FIG. 1 about the fixed pivot 3 to a fully opened position 1'. The time during which the shutter blade 1 remains open is controlled by the return spring 7. When the shutter blade 1 is returned clockwise in FIG. 1 back to its closed position against the fixed stop 9, it is likely that the mechanical shock to the blade caused by the blade abruptly hitting the stop will induce the blade to bounce off the stop. As a result, the shutter blade 1 will swing counterclockwise in FIG. 1 possibly to a partially opened position 1", thereby effecting an undesired second exposure of the film section that was previously exposed.